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FOCUS

Sampling strategies for biological communities

GRADE LEVEL

7-8

FOCUS QUESTION

How well do biological samples represent the actual biological communities from which they are taken?

LEARNING OBJECTIVES

Students will be able to identify the three realms of the Arctic Ocean, and describe the relationships between these realms.

Students will be able to discuss the advantages and limitations of sampling techniques to study biologi-cal communities.

ADDITIONAL INFORMATION FOR TEACHERS OF DEAF STUDENTS

In addition to the words listed as key words, the fol-lowing words should be part of the vocabulary list.Benthic Pelagic Zooplankton Phytoplankton SympagicPrimary productivityContinental shelfDiatoms AlgaePhotosynthesis Chemosynthesis Primary production

Submarine Brine channels

There are no formal signs in American Sign Language for any of the key words and many are difficult to lipread. Having the vocabulary list on the board as a reference during the lesson will be extremely helpful. Additional information regard-ing ROV‚s and ABE can be added and will help students understand the potential limits and advan-tages of sampling.

MATERIALS

Paper grid cells; ideally, make one set for each student group (copy and cut from master includ-ed in lesson plan)

Blank “Sampling Plan Sheets,” one for each stu-dent group (copy from master included in lesson plan)

Blank “Sampling Plan Data Sheets,” one for each student group (copy from master included in les-son plan)

“Complete List of All Organisms in the Model Community;” copy this onto an overhead trans-parency if desired to use during discussion of results

Table of random numbers, or telephone directory

AUDIO/VISUAL MATERIALS

None, unless an overhead projector is desired to facilitate discussions

TEACHING TIME

One or two 45-minute class periods

Arctic Ocean Exploration

Would You Like a Sample?

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Arctic Ocean Exploration—Grades 7–8Sampling strategies for biological communities oceanexplorer.noaa.gov

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oceanexplorer.noaa.govArctic Ocean Exploration—Grades 7–8


SEATING ARRANGEMENT

Groups of four or five students

MAXIMUM NUMBER OF STUDENTS

30

KEY WORDS

PelagicBenthicSympagicTransectQuadratGrid

BACKGROUND INFORMATION

The Arctic Ocean is the smallest of the world’s four ocean basins with a total area of about 5.4 million square miles or 14 million square kilometers (roughly 1.5 times the size of the United States), and is bor-dered by Greenland, Canada, Alaska, Norway, and Russia. The Arctic Ocean has the widest continental shelf of any ocean, extending 750 mi (1,210 km) from the coast of Siberia, but also has areas that are quite deep (the average depth is 12,000 ft (3,658 m) and the maximum depth is 17,850 ft (5,441 m)). The Chukchi Sea provides a connection with the Pacific Ocean via the Bering Strait, but this connection is very narrow and shallow, so most water exchange is with the Atlantic Ocean via the Greenland Sea.

The floor of the Arctic Ocean is divided by three submarine ridges (Alpha Ridge, Lomonosov Ridge, and the Arctic Mid-Oceanic Ridge), one of which (the Lomonosov Ridge) creates a relatively isolated area known as the Canadian Basin. This area is particularly interesting to scientists because its isolation could mean that it contains unique life forms that are found nowhere else on Earth. But the Arctic Ocean is not easily explored; it is almost entirely covered with ice for eight months of the year, a drifting polar ice pack covers the central and western portions year-round, and sea temper-ature seldom rises above 0°C. Although the Arctic is still the world’s least explored ocean, new expe-ditions are about to give us much greater knowl-

edge of the mysteries of this polar frontier.

At this point, we know that there are at least three distinct biological communities in the Arctic Ocean. The Sea-Ice Realm includes plants and animals that live on, in, and just under the ice that floats on the Arctic Ocean’s surface. Because only 50% of this ice melts in the summer, ice flows can exist for many years and can reach a thickness of more than six ft. (2 m). Sea ice is not usually solid like an ice cube, but is riddled with a network of tun-nels, called brine channels, that range in size from microscopic (a few thousandths of a millimeter) to more than an inch in diameter. Diatoms and algae inhabit these channels and obtain energy from sun-light to produce biological material through photo-synthesis. Bacteria, viruses, and fungi also inhabit the channels, and together with diatoms and algae provide an energy source (food) for flatworms, crustaceans, and other animals. This community of organisms is called sympagic, which means “ice-associated.” Partial melting of sea ice during the summer months produces ponds on the ice surface that contain their own communities of organisms. Melting ice also releases organisms and nutrients that interact with the ocean water below the ice.

The Pelagic Realm includes organisms that live in the water column between the ocean surface and the bottom. Melting sea ice allows more light to enter the sea, and algae grow rapidly since the sun shines for 24 hours a day during the summer. These algae provide energy for a variety of float-ing animals (zooplankton) that include crustaceans and jellyfishes. Zooplankton, in turn, are the energy source for larger pelagic animals including fishes, squids, seals, and whales.

When pelagic organisms die, they settle to the ocean bottom as detritus, and become the energy source for inhabitants of the Benthic Realm. Sponges, bivalves, crustaceans, polychaete worms, sea anemones, bryozoans, tunicates, and ascidians are common members of Arctic benthic communi-ties. These animals provide energy for bottom-feed-

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ing fishes, whales, and seals.

Most of our knowledge about biological communities in the Arctic Ocean comes from studies on portions of the Ocean near the continental shelves. Very little research has been done on the sea ice, pelagic, and benthic realms in the deepest parts of the Arctic Ocean. These areas are the focus of the Arctic Ocean Expedition.

One of the classic problems faced by research-ers working on biological communities is how best to sample the living organisms that make up these communities. Even if all of the organisms are large enough to see and are out in the open on a flat surface, it is usually impractical to count every single organism present. So researchers have developed various systems for taking samples from a communi-ty, and then using these samples to draw conclusions about the community as a whole. There is always a question, though, of how well the samples represent the community. The situation becomes even more complicated when organisms are hidden under rocks or in sediment, or are very small, or very large, or very fast. New technologies, including remotely oper-ated vehicles (ROVs), underwater video recorders, high resolution digital cameras, and side scan sonar are being used by researchers on the Arctic Ocean Expedition to overcome some of the difficulties of sampling biological communities. Still, the research-ers know that some organisms will go undetected.

LEARNING PROCEDURE

In this activity, students will use several common sam-pling techniques to investigate an “unknown” biologi-cal community, and will compare the strengths and weaknesses of these techniques in giving an accurate impression of the community’s organisms.

1. Arrange one or more sets of paper grid cells face down on a table (an area of about 30 in. x 30 in. will be needed for each set). Be sure that cells are arranged in grid order, so that the cell labeled “1,1” is in the lower left corner, and the cell labeled “20,20” is in the upper right corner. Ideally, have one set of

cells for each student group; this will make the activity go much more quickly!

2. Review Background Information on the Arctic Ocean and its three known biological realms. Emphasize that the Expedition will be inves-tigating many areas that have never been explored before, and that researchers have only a general idea of what they will find. Tell the students that their task is to develop a sampling plan for a benthic community 10,000 feet deep the Arctic Ocean. Side scan sonar indicates that the area is almost completely flat, with no large rocks or other distinct features. Using precision mapping and global positioning equipment, the site has been divided into a grid of 400 squares. The overall plan is to send an ROV to the site to collect samples, but because there are many other areas to investigate, sampling time is limited, and only 25 grid squares can be sampled from this site. The good news is that the ROV is equipped with photographic and video equipment, as well as a variety of manipulator arms and sampling devices, so we have a good chance of detecting the most of the non-microscopic organisms present in the community.

3. Lead a discussion with the students of how they might arrange their sampling program. One of the most commonly used sampling systems is to establish one or more lines (called transects) across the study area, and then take samples at fixed intervals along the transect line. For visual surveys, these samples are often taken within a square area of fixed size (called a quadrat). In the case of our model community, individual quadrats are represented by the individual grid squares.

As an alternative to the transect technique,

students should consider the possibility of collecting samples randomly throughout the community, and discuss the advantages and

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disadvantages of each approach. To apply a random sampling system to the model com-munity, each grid square should be assigned a pair of coordinates beginning with 1,1 (for the square in the lower left corner) and end-ing with 20,20 (for the square in the upper right corner), just as one would describe coordinates on a piece of graph paper. Then grid squares to be sampled would be identi-fied using a table of random numbers taken four at a time (so if the first four numbers in the table were 1,3,0,7 the first square to be sampled would be 13 squares across and seven squares up).

Coordinate pairs greater than 20,20 are skipped, and the process continued until 25 usable coordinate pairs have been selected. If a table of random numbers is not available, use a telephone directory, using the last digit of each number beginning with the first listing in the directory.

Once the students have collected their data, they may be somewhat overwhelmed by three pages of numbers and strange names that they need to process. One of the most impor-tant lessons to be learned through this activity is how to manage this sort of data set. The key to good data analysis is to define exactly what information is needed from the data, before the data are collected. Be sure the stu-dents understand that for this activity we want to know:

(a) what species groups are present in the model community;

(b) the relative abundance of these groups; and(c) which species groups tend to occur together

(because these associations give clues as to how different species groups may be interact-ing in the community).

4. Have each student group select a sampling technique, and diagram their sampling plan on a blank “Sampling Plan Sheet.” Try to

have some groups use a random sampling system, and others use a transect system.

5. Have each group turn over the paper grid cells that correspond to their sampling plan, and record the results on a “Sampling Plan Data Sheet.” If more than one group is using a set of cells, have the groups work one at a time (groups using a transect system could begin while groups using a random system are identifying their sample cells with a ran-dom numbers table). Be sure all of the cells are face down again before another group begins to collect data.

6. Have each group analyze their data to answer the three questions listed in Step 3. First, make a list of all the species groups found; this answers question (a).

Next, tally the number of quadrats in which each group occurred. Classify each group as “Abundant” if it occurred in more than 50% of the samples, “Common” if it occurred in 20% but less than 50% of the samples, and “Rare” if it occurred in less than 20% of the samples. This answers question (b).

Finally, identify species groups that are com-monly found together. One way to do this is to make a matrix, listing all species groups in vertical columns, and all species groups in horizontal rows. In each cell of the matrix, fill in the number of quadrats in which each species group was found with all the other groups. For example:

Group A Group B Group C Group D etc.

Group A 20 3 18 12

Group B 15 5 10

Group C 23 1

Group D 14

etc.

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So, species Group A, which was found in 20 quadrats, is strongly associated with Group C, which was found in 23 quadrats, and pos-sibly with Group D which was found in 14 quadrats. Species Group B, which was found in 15 quadrats, was strongly associated with Group D, but not with the other two groups.

This gives an answer to question (c).

7. Have each group present a summary of their data that includes: the total number of spe-cies found, the relative abundance of each species, and which species appear together in more than three samples. Record these summaries on a marker board, flip chart, or overhead transparency. Lead a discussion that includes

(a) comparing the results of the different tech-niques;

(b) speculation about what features of the model community might lead to the results they obtained;

(c) how organisms are actually distributed in nature (more often clumped than randomly distributed); and

(d) how the students’ results could be used to design a follow-up sampling program.

8. Compare the students’ results with the “Complete List of All Organisms in the Model Community.” This sort of list is almost never available in actual

research situations, but should show how difficult it is for a single sampling program to detect all of the species in a community. Be sure the students under-stand that they were able to sample 1/16th of the entire model community, and that the coverage possible with most sampling programs is much less.

THE BRIDGE CONNECTION

www.vims.edu/bridge/polar.htmlwww.vims.edu/bridge/benthos.html

THE “ME” CONNECTION

Have students write a short essay or prepare a brief oral presentation on how knowledge of unex-plored biological communities might benefit them personally, and/or why they think this knowledge is (or is not) important. Ask students to share their thoughts with the rest of the class.

CONNECTIONS TO OTHER SUBJECTS

Mathematics, Earth Science, Physical Science

EVALUATION

Individual sampling plans and data summaries pre-pared by each student group may be collected to assess the thoroughness of their work. Additionally, students may be asked to define key words and/or address discussion points 6a, b, c, and d in writing before participating in a group discussion.

EXTENSIONS

1. Have students visit http://oceanexplorer.noaa.gov to keep up to date with the real-time explora-tion of the deep Arctic Ocean, and to find out what organisms researchers actually find in the three realms.

2. Have students design an investigation to dis-cover lifeforms on one of the moons of Jupiter. Ask them to consider as many different forms as possible, and to discuss how the techniques used by an expedition to discover new life-forms might be different from techniques used to investigate a known biological community.

3. Visit http://www.ropos.com to find out about the ROV being used on the Arctic Ocean Expedition to explore biological communities.

4. Have students research species groups that are unfamiliar, and present a brief report describ-ing these groups.

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Arctic Ocean Exploration—Grades 7–8Sampling strategies for biological communities oceanexplorer.noaa.gov oceanexplorer.noaa.gov

Arctic Ocean Exploration—Grades 7–8Sampling strategies for biological communities

Student HandoutRESOURCES

http://oceanexplorer.noaa.gov – Follow the Arctic Ocean Expedition as documentaries and discoveries are posted each day for your classroom use.

http://www.sciencegems.com/earth2.html – Science education resources

http://www-sci.lib.uci.edu/HSG/Ref.html – References on just about everything

NATIONAL SCIENCE EDUCATION STANDARDS

Content Standard A: Science As Inquiry• Abilities necessary to do scientific inquiry• Understanding about scientific inquiry

Content Standard C: Life Science• Populations and ecosystems

FOR MORE INFORMATION

Paula Keener-Chavis, National Education Coordinator/Marine BiologistNOAA Office of ExplorationHollings Marine Laboratory331 Fort Johnson Road, Charleston SC 29412843.762.8818843.762.8737 (fax)[email protected]

ACKNOWLEDGEMENTS

This lesson plan was produced by Mel Goodwin, PhD, The Harmony Project, Charleston, SC for the National Oceanic and Atmospheric Administration. If reproducing this lesson, please cite NOAA as the source, and provide the following URL: http://oceanexplorer.noaa.gov

http://oceanexplorer.noaa.gov

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Arctic Ocean Exploration—Grades 7–8Sampling strategies for biological communities oceanexplorer.noaa.gov oceanexplorer.noaa.gov

Arctic Ocean Exploration—Grades 7–8Sampling strategies for biological communities

Student Handout

Quadrat 1,5Species Groups Found:

PolychaetesAmphipods

Sand DollarsSipunculidsTunicates

Brittle StarsSea Anemones

SnailsCumaceans





Snails





Snails





Snails





SnailsCumaceans





SnailsCumaceans





SnailsCumaceans





SnailsCumaceans





SnailsCumaceans





SnailsCumaceans





SnailsCumaceans





SnailsCumaceans





SnailsCumaceans





Snails





Snails





Snails





Snails





Snails





Snails





Snails

Grid Cells, page 1



Student Handout



Student Handout


BryozoansSea Cucumbers

Sea UrchinsSipunculidsTunicates


SnailsEctoprocta





SnailsEctoprocta





SnailsEctoprocta





SnailsEctoprocta





SnailsEctoprocta





SnailsEctoprocta



Sand DollarsAscidiansTunicates


Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





SnailsEctoprocta





SnailsEctoprocta





SnailsEctoprocta





SnailsEctoprocta

Grid Cells, page 2



Student Handout



Student Handout





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails

Grid Cells, page 3



Student Handout



Student Handout





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails





Snails



Sea UrchinsAscidiansTunicates

Snails




Snails




Snails




Snails




Snails





Snails





Snails





Snails





Snails

Grid Cells, page 4



Student Handout



Student Handout




SnailsNemertine Worms
























Snails




Snails




Snails




Snails




Snails




Snails




Snails




Snails




Snails




Snails

















Grid Cells, page 5



Student Handout



Student Handout





IsopodsCumaceans





IsopodsCumaceans





IsopodsCumaceans





IsopodsCumaceans





IsopodsCumaceans





IsopodsCumaceans





Isopods





Isopods





Isopods





Isopods





Isopods





Isopods





Isopods





Isopods





Isopods





Isopods





IsopodsCumaceans





IsopodsCumaceans





IsopodsCumaceans





IsopodsCumaceans

Grid Cells, page 6



Student Handout



Student Handout





Isopods





Isopods





Isopods





Isopods





Isopods


PolychaetesAmphipodsSea UrchinsSipunculidsTunicatesIsopods





























Grid Cells, page 7



Student Handout



Student Handout



Ectoprocts



Ectoprocts



Ectoprocts



Ectoprocts



Ectoprocts



Ectoprocts



Sand DollarsAscidiansTunicatesIsopods






























Ectoprocts



Ectoprocts



Ectoprocts



Ectoprocts

Grid Cells, page 8



Student Handout



Student Handout



































PolychaetesAmphipodsSea Urchins

AscidiansTunicatesIsopods

























Grid Cells, page 9



Student Handout



Student Handout




Nemertine Worms




Nemertine Worms




Nemertine Worms




Nemertine Worms




Nemertine Worms




Nemertine Worms


































Nemertine Worms




Nemertine Worms




Nemertine Worms




Nemertine Worms

Grid Cells, page 10



Student Handout



Student Handout



Sand DollarsSipunculids

BivalvesPolyplacophorans













































































Grid Cells, page 11



Student Handout



Student Handout





Priapulids





Priapulids



Sea UrchinsSipunculids


Priapulids













































Priapulids





Priapulids





Priapulids





Priapulids





Priapulids





Priapulids





Priapulids

Grid Cells, page 12



Student Handout



Student Handout



























Sand DollarsAscidiansBivalves

Polyplacophorans




Polyplacophorans




Polyplacophorans




Polyplacophorans




Polyplacophorans




Polyplacophorans




Polyplacophorans




Polyplacophorans




Polyplacophorans




Polyplacophorans

















Grid Cells, page 13



Student Handout



Student Handout




PolyplacophoransBarnacles
























Polyplacophorans



Sea UrchinsAscidiansBivalves
















Polyplacophorans




Polyplacophorans




Polyplacophorans




Polyplacophorans

















Grid Cells, page 14



Student Handout



Student Handout





























































Grid Cells, page 15



Student Handout



Student Handout

















































































Grid Cells, page 16



Student Handout



Student Handout





Priapulida





Priapulida


PolychaetesAmphipodsSea UrchinsSipunculids


Priapulida


































Priapulida




Priapulida




Priapulida




Priapulida





Priapulida





Priapulida





Priapulida

Grid Cells, page 17



Student Handout



Student Handout





























































Grid Cells, page 18



Student Handout



Student Handout




Barnacles




Barnacles




Barnacles




Barnacles




Barnacles




Barnacles






AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves
















Barnacles




Barnacles




Barnacles




Barnacles

Grid Cells, page 19



Student Handout



Student Handout



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves



AscidiansBivalves

Grid Cells, page 20



Student Handout



Student Handout

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

All Quadrats in Columns 1 - 5

Contain: Sand Dollars Sipunculids


Contain: Sand Dollars Sipunculids


Contain: Sea UrchinsAscidians


Contain: Sea UrchinsAscidians

All Quadrats inRows 16 - 20

Contain: Bivalves


Contain: Bivalves


Contain: Tunicates


Contain: Tunicates

ABCD

EFGH

IJKL

MNOP

The 25 quadrats labelled C, D, G, H, and L also contain Brittle Stars and Sea AnemonesThe 25 quadrats labelled D, H, L and P also contain SnailsThe 25 quadrats labelled C, G, K, and O also contain IsopodsThe 25 quadrats labelled A, B, E, F,, and J also contain Polyplacophora

These contain Polychaetes and Amphipods These contain Bryozoans and Sea Cucumbers

These quadrats also contain Cumaceans These quadrats also contain Priapulida

These quadrats also contain Ectoprocta

These quadrats also contain Nemertine Worms

Complete List of All Organisms in the Model Community



Student Handout



Student Handout

Sampling Plan Sheet

Mark 25 quadrats to be sampled.

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19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20



Student Handout



Student Handout

Quadrat ,

Species Groups Present:

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Quadrat ,


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Quadrat ,


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Quadrat ,


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Sampling Plan Data Sheet

Quadrat ,


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Quadrat ,


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Quadrat ,


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